Hello again I have done a new thread as I have now found out new information which has cured my problem and may also give thoughts for others with similar problems. the inverter I am using is a self tuning one and when I told the supplier that the motor plate power info said 6.3 Amps at 230 volt I should have said 220 volt what was happening was that with single phase supply in the UK being 230- 240 volt nominal volyage actually runs more like 215 -230 volt at 50 hz the motors on a series 1 cnc bridgeport are 220 volt 60 hz so by resetting the voltage input maximum to 215 volts and the frequency to 60 HZ maximum output voltage to 220 volt I now have the inverter running at 3.7 - 3.8 amps for the full speed range ( unloaded ) so giving alot more free ampage to go at from the inverter supply before starting to get anywhere near the overloading current trips. this all came to light after I went to see the motor rewind company that this info came to light because although the repairer was not up to scratch on inverters he new one heck of alot about motor characteristics and he said that once you go above nominal voltage the amps start to rise appreciably hence my problem of running 230volt at 6.3 amps all down to saturation mylad he said just goes to show he said motor windings have'nt altered that much in the last 50 years so I hope this helps others who may have come up against similar problems. Cheers for now COLIN1544